The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structures.
In the past, the semiconductor industry utilized various methods and structures to form power supply controllers that would assist in regulating an output voltage to a desired value. In some power supply configurations, two transistors were connected in a stacked configuration or half-bridge circuit configuration in order to drive an inductor and form the output voltage. Some examples of such power supply configurations were LLC resonant power converters and other resonant type power converters. Each of the two transistors in the half-bridge circuit were driven by separate transistor drivers. Typically, the two transistors were switched synchronously so that the two transistors were not enabled at the same time. In order to ensure that one transistor turned off before the next transistor turned on, delay circuits or logic circuits were used to provide a dead time between turning off one transistor and turning on the other transistor. This a dead time ensured that shoot-through currents were not formed by simultaneous conduction of both transistors. The duration of the dead time was a fixed time and usually was selected for the lightest load condition in order to ensure the elimination of shoot-through currents. For the case of resonant type power converters, the dead times were prolonged which allowed voltage swing of the resonant LC tank circuit to change the voltage at the center of the half-bridge. This dead time caused energy losses in the half-bridge circuit which reduced the efficiency of the system using the circuit.
Accordingly, it is desirable to have a power supply controller that more efficiently reduces shoot-through current and that controls shoot-through current and resonant switching without imposing a fixed dead-time.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein, current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action. For clarity of the drawings, doped regions of device structures are illustrated as having generally straight line edges and precise angular corners. However, those skilled in the art understand that due to the diffusion and activation of dopants, the edges of doped regions generally may not be straight lines and the corners may not be precise angles.